U.S. patent application number 16/812435 was filed with the patent office on 2021-03-04 for light detector, light detection system, lidar device, and vehicle.
This patent application is currently assigned to KABUSHIKI KAISHA TOSHIBA. The applicant listed for this patent is KABUSHIKI KAISHA TOSHIBA. Invention is credited to lkuo FUJIWARA, Koichi ISHII, Honam KWON, Kazuhiro SUZUKI.
Application Number | 20210063545 16/812435 |
Document ID | / |
Family ID | 1000004702214 |
Filed Date | 2021-03-04 |
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United States Patent
Application |
20210063545 |
Kind Code |
A1 |
KWON; Honam ; et
al. |
March 4, 2021 |
LIGHT DETECTOR, LIGHT DETECTION SYSTEM, LIDAR DEVICE, AND
VEHICLE
Abstract
According to one embodiment, a light detector includes a
conductive layer, a first element, a second element, a first
member, a first insulating part, and a second insulating part. The
conductive layer includes a first conductive portion and a second
conductive portion. The first element includes a first
semiconductor layer and a second semiconductor layer. The second
element includes a fourth semiconductor layer and a fifth
semiconductor layer. The first member is provided between the first
element and the second element and electrically connected to the
conductive layer. The first member is conductive. The first
insulating part is provided between the first element and the first
member. The second insulating part is provided between the second
element and the first member.
Inventors: |
KWON; Honam; (Kawasaki,
JP) ; ISHII; Koichi; (Kawasaki, JP) ;
FUJIWARA; lkuo; (Yokohama, JP) ; SUZUKI;
Kazuhiro; (Meguro, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOSHIBA |
Minato-ku |
|
JP |
|
|
Assignee: |
KABUSHIKI KAISHA TOSHIBA
Minato-ku
JP
|
Family ID: |
1000004702214 |
Appl. No.: |
16/812435 |
Filed: |
March 9, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01S 7/4865 20130101;
H01L 31/02005 20130101; G01S 7/4863 20130101; G01S 17/931
20200101 |
International
Class: |
G01S 7/4863 20060101
G01S007/4863; H01L 31/02 20060101 H01L031/02; G01S 17/931 20060101
G01S017/931; G01S 7/4865 20060101 G01S007/4865 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 29, 2019 |
JP |
2019-157217 |
Claims
1. A light detector, comprising: a conductive layer including a
first conductive portion and a second conductive portion; a first
element including a first semiconductor layer and a second
semiconductor layer, the first semiconductor layer being of a first
conductivity type, the second semiconductor layer being of a second
conductivity type and being provided between the first conductive
portion and the first semiconductor layer in a second direction
crossing a first direction, the first direction being from the
first conductive portion toward the second conductive portion; a
second element including a fourth semiconductor layer and a fifth
semiconductor layer, the fourth semiconductor layer being of the
first conductivity type, the fifth semiconductor layer being of the
second conductivity type and being provided between the second
conductive portion and the fourth semiconductor layer in the second
direction; a first member provided between the first element and
the second element and electrically connected to the conductive
layer, the first member being conductive; a first insulating part
provided between the first element and the first member; and a
second insulating part provided between the second element and the
first member.
2. A light detector, comprising: a conductive layer including a
first conductive portion and a second conductive portion; a first
element including a first semiconductor layer, a second
semiconductor layer, and a third semiconductor layer, the first
semiconductor layer being of a first conductivity type, the second
semiconductor layer and the third semiconductor layer being of a
second conductivity type, the second semiconductor layer being
provided between the first conductive portion and the first
semiconductor layer in a second direction crossing a first
direction, the third semiconductor layer being provided between the
first conductive portion and the second semiconductor layer, the
first direction being from the first conductive portion toward the
second conductive portion; a second element including a fourth
semiconductor layer, a fifth semiconductor layer, and a sixth
semiconductor layer, the fourth semiconductor layer being of the
first conductivity type, the fifth semiconductor layer and the
sixth semiconductor layer being of the second conductivity type,
the fifth semiconductor layer being provided between the second
conductive portion and the fourth semiconductor layer in the second
direction, the sixth semiconductor layer being provided between the
second conductive portion and the fifth semiconductor layer; a
first insulating part provided between the first element and the
second element; a second insulating part provided between the first
insulating part and the second element; and a first member provided
between the first insulating part and the second insulating part, a
light transmittance of the first member being lower than a light
transmittance of the third semiconductor layer and lower than a
light transmittance of the sixth semiconductor layer.
3. The detector according to claim 1, wherein the first member
contacts the conductive layer.
4. The detector according to claim 1, further comprising a first
wiring part electrically connected to the first semiconductor
layer, a portion of the first element and a portion of the first
insulating part being positioned between the conductive layer and
the first wiring part in the second direction.
5. The detector according to claim 4, further comprising: a first
connection wiring part; and a first conductive part connected
between the first wiring part and the first connection wiring part,
an electrical resistance of the first conductive part being higher
than an electrical resistance of the first wiring part and higher
than an electrical resistance of the first connection wiring part,
a position of the first connection wiring part being different from
a position of the first member when viewed from the second
direction.
6. A light detector, comprising: a conductive layer including a
first conductive portion and a second conductive portion; a first
element including a first semiconductor layer and a second
semiconductor layer, the first semiconductor layer being of a first
conductivity type, the second semiconductor layer being of a second
conductivity type and being provided between the first conductive
portion and the first semiconductor layer in a second direction
crossing a first direction, the first direction being from the
first conductive portion toward the second conductive portion; a
second element including a fourth semiconductor layer and a fifth
semiconductor layer, the fourth semiconductor layer being of the
first conductivity type, the fifth semiconductor layer being of the
second conductivity type and being provided between the second
conductive portion and the fourth semiconductor layer in the second
direction; a first member provided between the first element and
the second element and between the first conductive portion and the
second conductive portion, the first member being conductive; an
insulating layer provided between the conductive layer and the
first member; a first insulating part provided between the first
element and the first member; and a second insulating part provided
between the second element and the first member.
7. The detector according to claim 6, further comprising a first
wiring part electrically connected to the first semiconductor layer
and the first member.
8. The detector according to claim 1, wherein the first element
further includes a third semiconductor layer provided between the
first conductive portion and the second semiconductor layer, the
third semiconductor layer being of the second conductivity type,
and the second element further includes a sixth semiconductor layer
provided between the second conductive portion and the fifth
semiconductor layer, the sixth semiconductor layer being of the
second conductivity type.
9. The detector according to claim 2, wherein an impurity
concentration of the second conductivity type in the third
semiconductor layer is lower than an impurity concentration of the
second conductivity type in the second semiconductor layer, and an
impurity concentration of the second conductivity type in the sixth
semiconductor layer is lower than an impurity concentration of the
second conductivity type in the fifth semiconductor layer.
10. The detector according to claim 2, wherein a thickness T1 in
the second direction of the first semiconductor layer, a thickness
T2 in the second direction of the second semiconductor layer, and a
thickness T3 in the second direction of the third semiconductor
layer satisfy T1+1.1.times.T2<L1 and L1<T1+T2+1.1.times.T3
when the thickness T2 is not more than 10 times the thickness T3,
and satisfy T1+1.1.times.T2<L1 and T1+T2+1.1.times.T3<L1 when
the thickness T2 is greater than 10 times the thickness T3.
11. The detector according to claim 2, wherein a length in the
second direction of the first member is greater than a thickness in
the second direction of the third semiconductor layer and not more
than 20 .mu.m.
12. The detector according to claim 1, further comprising a
semiconductor part provided between the first insulating part and
the first member, between the second insulating part and the first
member, or between the first insulating part and the first member
and between the second insulating part and the first member.
13. The detector according to claim 1, wherein at least one of the
first insulating part or the second insulating part contacts the
first member.
14. The detector according to claim 1, wherein a distance in the
first direction between the first insulating part and the second
insulating part is not less than 0.5 .mu.m and not more than 10
.mu.m.
15. The detector according to claim 1, wherein the first member
includes at least one selected from the group consisting of
tungsten, aluminum, and an alloy, the alloy including aluminum and
copper.
16. A light detection system, comprising: the light detector
according to claim 1, and a distance measuring circuit calculating,
from an output signal of the light detector, a time-of-flight of
light.
17. A lidar device, comprising: a light source irradiating light on
an object; and the light detection system according to claim 16
detecting light reflected by the object.
18. The lidar device according to claim 17, further comprising an
image recognition system generating a three-dimensional image based
on an arrangement relationship of the light source and the light
detector.
19. A vehicle, comprising the lidar device according to claim
17.
20. A vehicle, comprising the lidar devices according to claim 17
at four corners of a vehicle body.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from Japanese Patent Application No. 2019-157217, filed on
Aug. 29, 2019; the entire contents of which are incorporated herein
by reference.
FIELD
[0002] Embodiments described herein relate generally to a light
detector, a light detection system, a lidar device, and a
vehicle.
BACKGROUND
[0003] A light detector detects light incident on an element
including a semiconductor. It is desirable to increase the
performance of the light detector.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 is a schematic plan view illustrating a light
detector according to a first embodiment;
[0005] FIG. 2A and FIG. 2B are schematic cross-sectional views
illustrating the light detector according to the first
embodiment;
[0006] FIG. 3A, FIG. 3B, FIG. 4A, and FIG. 4B are schematic
cross-sectional views illustrating manufacturing processes of the
light detector according to the first embodiment;
[0007] FIG. 5A and FIG. 5B are schematic cross-sectional views
illustrating a light detector according to a second embodiment;
[0008] FIG. 6 is a schematic plan view illustrating a light
detector according to a third embodiment;
[0009] FIG. 7 is a schematic plan view illustrating a light
detector according to a fourth embodiment;
[0010] FIG. 8 is a schematic plan view illustrating a light
detector according to a fifth embodiment;
[0011] FIG. 9A and FIG. 9B are schematic cross-sectional views
illustrating the light detector according to the fifth
embodiment;
[0012] FIG. 10A and FIG. 10B are schematic cross-sectional views
illustrating a light detector according to a sixth embodiment;
[0013] FIG. 11A and FIG. 11B are schematic cross-sectional views
illustrating a light detector according to a seventh
embodiment;
[0014] FIG. 12 is a schematic view illustrating a lidar (Laser
Imaging Detection and Ranging) device according to an eighth
embodiment;
[0015] FIG. 13 is a drawing for describing the detection of the
detection object of the lidar device; and
[0016] FIG. 14 is a schematic top view of a vehicle including the
lidar device according to the eighth embodiment.
DETAILED DESCRIPTION
[0017] According to one embodiment, a light detector includes a
conductive layer, a first element, a second element, a first
member, a first insulating part, and a second insulating part. The
conductive layer includes a first conductive portion and a second
conductive portion. The first element includes a first
semiconductor layer and a second semiconductor layer. The first
semiconductor layer is of a first conductivity type. The second
semiconductor layer is of a second conductivity type and is
provided between the first conductive portion and the first
semiconductor layer in a second direction crossing a first
direction. The first direction is from the first conductive portion
toward the second conductive portion. The second element includes a
fourth semiconductor layer and a fifth semiconductor layer. The
fourth semiconductor layer is of the first conductivity type. The
fifth semiconductor layer is of the second conductivity type and is
provided between the second conductive portion and the fourth
semiconductor layer in the second direction. The first member is
provided between the first element and the second element and
electrically connected to the conductive layer. The first member is
conductive. The first insulating part is provided between the first
element and the first member. The second insulating part is
provided between the second element and the first member.
[0018] Embodiments of the invention will now be described with
reference to the drawings.
[0019] The drawings are schematic or conceptual; and the
relationships between the thicknesses and widths of portions, the
proportions of sizes between portions, etc., are not necessarily
the same as the actual values thereof. The dimensions and/or the
proportions may be illustrated differently between the drawings,
even in the case where the same portion is illustrated.
[0020] In the drawings and the specification of the application,
components similar to those described thereinabove are marked with
like reference numerals, and a detailed description is omitted as
appropriate.
First Embodiment
[0021] FIG. 1 is a schematic plan view illustrating a light
detector according to a first embodiment.
[0022] FIG. 2A and FIG. 2B are schematic cross-sectional views
illustrating the light detector according to the first
embodiment.
[0023] FIG. 2A is an A1-A2 cross section of FIG. 1. FIG. 2B is a
B1-B2 cross section of FIG. 1.
[0024] As shown in FIG. 1 and FIG. 2A, the light detector 110
according to the first embodiment includes a conductive layer 10, a
first element 21, a second element 22, a first insulating part 31,
a second insulating part 32, and a conductor 40. The first
insulating part 31 surrounds the first element 21. The second
insulating part 32 surrounds the second element 22. The conductor
40 surrounds the first insulating part 31 and the second insulating
part 32. The first element 21, the second element 22, the first
insulating part 31, the second insulating part 32, and the
conductor 40 are provided on the conductive layer 10. Herein, the
direction from the back toward the front in the page surface of
FIG. 1 is taken as "up".
[0025] Carriers are generated in the first element 21 when light is
incident on the first element 21. Similarly, carriers are generated
in the second element 22 when light is incident on the second
element 22. The light detector 110 detects the light incident on
the elements as electrical signals.
[0026] The conductive layer 10 includes a first conductive portion
11 and a second conductive portion 12. The direction from the first
conductive portion 11 toward the second conductive portion 12 is
taken as a first direction. For example, the first direction is
along an X-direction shown in FIG. 1. One direction perpendicular
to the X-direction is taken as a Y-direction. A direction
perpendicular to the X-direction and the Y-direction is taken as a
Z-direction. A direction that crosses the first direction is taken
as a second direction. For example, the second direction is along
the Z-direction. A direction crossing a plane parallel to the first
direction and the second direction is taken as a third direction.
For example, the third direction is along the Y-direction.
Hereinbelow, a case will be described where the first direction,
the second direction, and the third direction are respectively
along the X-direction, the Z-direction, and the Y-direction.
[0027] The first element 21 includes a first semiconductor layer
21a of a first conductivity type, a second semiconductor layer 21b
of a second conductivity type, and a third semiconductor layer 21c
of the second conductivity type. The first semiconductor layer 21a,
the second semiconductor layer 21b, and the third semiconductor
layer 21c spread along the X-direction and the Y-direction. The
second semiconductor layer 21b and the third semiconductor layer
21c are provided between the first semiconductor layer 21a and the
first conductive portion 11. The first semiconductor layer 21a is
separated from the first conductive portion 11 in the Z-direction.
The second semiconductor layer 21b is provided between the first
conductive portion 11 and the first semiconductor layer 21a in the
Z-direction. The third semiconductor layer 21c is provided between
the first conductive portion 11 and the second semiconductor layer
21b in the Z-direction and surrounds the first semiconductor layer
21a and the second semiconductor layer 21b along the X-Y plane. For
example, the third semiconductor layer 21c contacts the first
conductive portion 11. The first semiconductor layer 21a, the
second semiconductor layer 21b, and the third semiconductor layer
21c are electrically connected to the first conductive portion
11.
[0028] The second element 22 includes a fourth semiconductor layer
22d of the first conductivity type, a fifth semiconductor layer 22e
of the second conductivity type, and a sixth semiconductor layer
22f of the second conductivity type. The fourth semiconductor layer
22d, the fifth semiconductor layer 22e, and the sixth semiconductor
layer 22f spread along the X-direction and the Y-direction. The
fifth semiconductor layer 22e and the sixth semiconductor layer 22f
are provided between the fourth semiconductor layer 22d and the
second conductive portion 12 in the Z-direction. The fourth
semiconductor layer 22d is separated from the second conductive
portion 12 in the Z-direction. The fifth semiconductor layer 22e is
provided between the second conductive portion 12 and the fourth
semiconductor layer 22d in the Z-direction. The sixth semiconductor
layer 22f is provided between the first conductive portion 11 and
the fifth semiconductor layer 22e in the Z-direction and surrounds
the fourth semiconductor layer 22d and the fifth semiconductor
layer 22e along the X-Y plane. For example, the sixth semiconductor
layer 22f contacts the second conductive portion 12. The fourth
semiconductor layer 22d, the fifth semiconductor layer 22e, and the
sixth semiconductor layer 22f are electrically connected to the
second conductive portion 12.
[0029] The conductive layer 10 spreads along the X-direction and
the Y-direction and is arranged in the Z-direction with the first
element 21 and the second element 22. For example, the potential of
the conductive layer 10 is controlled via the conductor 40
described below. Also, the potential of the second semiconductor
layer 21b and the potential of the fifth semiconductor layer 22e
can be controlled by controlling the potential of the conductive
layer 10. By controlling the potential of the second semiconductor
layer 21b and the potential of the fifth semiconductor layer 22e,
voltages are applied between the first semiconductor layer 21a and
the second semiconductor layer 21b and between the fourth
semiconductor layer 22d and the fifth semiconductor layer 22e. For
example, the first element 21 and the second element 22 function as
avalanche photodiodes.
[0030] For example, the first conductivity type is an n-type; and
the second conductivity type is a p-type. The first conductivity
type may be the p-type; and the second conductivity type may be the
n-type. The impurity concentration of the second conductivity type
in the third semiconductor layer 21c is lower than the impurity
concentration of the second conductivity type in the second
semiconductor layer 21b. Thereby, carriers that are generated in
the third semiconductor layer 21c move into the second
semiconductor layer 21b and undergo avalanche multiplication. The
impurity concentration of the second conductivity type in the sixth
semiconductor layer 22f is lower than the impurity concentration of
the second conductivity type in the fifth semiconductor layer 22e.
Thereby, carriers that are generated in the sixth semiconductor
layer 22f move easily into the fifth semiconductor layer 22e; and
crosstalk can be reduced.
[0031] The direction from the first element 21 toward the second
element 22 is along the X-direction. For example, the direction
from the first semiconductor layer 21a toward the fourth
semiconductor layer 22d is along the X-direction. The direction
from the second semiconductor layer 21b toward the fifth
semiconductor layer 22e is along the X-direction. The direction
from the third semiconductor layer 21c toward the sixth
semiconductor layer 22f is along the X-direction.
[0032] The conductor 40 is provided around the first element 21 and
the second element 22 along the X-Y plane. In other words, the
conductor 40 surrounds the first element 21 and the second element
22. In the example shown in FIG. 1, FIG. 2A, and FIG. 2B, one
unbroken conductor 40 is provided to be continuous around the first
element 21 and the second element 22. The configuration is not
limited to the example; multiple conductors 40 may be arranged to
be separated from each other around the first element 21 and the
second element 22; and the first element 21 and the second element
22 may be surrounded with the multiple conductors 40. However, to
reduce the crosstalk and reduce the resistance of the conductor 40,
it is favorable for the first element 21 and the second element 22
to be surrounded continuously with one conductor 40.
[0033] Herein, "surround" includes not only the case where an
unbroken component continuously surrounds another component, but
also includes the case where multiple components are separated from
each other and arranged around the other component. For example,
the other component can be considered to be surrounded with the
multiple components when the other component is positioned inside a
path obtained by tracing along the multiple components.
[0034] It is favorable for the length in the Z-direction of the
conductor 40 to be longer than the length in the Z-direction of the
first element 21 and longer than the length in the Z-direction of
the second element 22. The length in the Z-direction of the
conductor 40 is greater than the thicknesses in the Z-direction of
the first semiconductor layer 21a, the second semiconductor layer
21b, and the third semiconductor layer 21c. The conductor 40
contacts the conductive layer 10. A portion of the conductor 40 may
pierce the conductive layer 10. The entire first element 21 and the
entire second element 22 are covered with the conductor 40 in the
X-direction and the Y-direction. In other words, the entire first
element 21 and the entire second element 22 overlap the conductor
40 when viewed from the X-direction and from the Y-direction.
[0035] The conductor 40 includes a first member 40a positioned
between the first element 21 and the second element 22 in the
X-direction. The first insulating part 31 is provided between the
first element 21 and the first member 40a in the X-direction. For
example, the first insulating part 31 is provided around the first
element 21 along the X-Y plane. In other words, the first
insulating part 31 surrounds the first element 21. Multiple first
insulating parts 31 may be arranged around the first element 21;
and the first element 21 may be surrounded with the multiple first
insulating parts 31.
[0036] The second insulating part 32 is provided between the second
element 22 and the first member 40a in the X-direction. For
example, the second insulating part 32 is provided around the
second element 22 along the X-Y plane. In other words, the second
insulating part 32 surrounds the second element 22. Multiple second
insulating parts 32 may be arranged around the second element 22;
and the second element 22 may be surrounded with the multiple
second insulating parts 32.
[0037] For example, the first insulating part 31 and the second
insulating part 32 contact the conductive layer 10. Because the
first insulating part 31 and the second insulating part 32 contact
the conductive layer 10, it is possible to reduce the crosstalk and
reduce the leakage current between the conductor 40 and the
elements.
[0038] A semiconductor part 25a is provided between the first
insulating part 31 and the first member 40a in the X-direction. A
semiconductor part 25b is provided between the second insulating
part 32 and the first member 40a in the X-direction. For example,
the semiconductor parts 25a and 25b are of the second conductivity
type.
[0039] The light detector 110 illustrated in FIG. 1, FIG. 2A, and
FIG. 2B further includes a third element 23, a fourth element 24, a
third insulating part 33, a fourth insulating part 34, first to
fourth wiring parts 51a to 51d, a first connection wiring part 52a,
a second connection wiring part 52b, first to fourth conductive
parts 53a to 53d, a wiring part 54, and first to third insulating
regions 61 to 63. The first to third insulating regions 61 to 63
are not illustrated in FIG. 1. In FIG. 1, the regions shown by
broken lines show the regions where the first element 21, the
second element 22, the third element 23, the fourth element 24, the
conductor 40, the first to fourth wiring parts 51a to 51d, the
first connection wiring part 52a, the second connection wiring part
52b, the first to fourth conductive parts 53a to 53d, and the
wiring part 54 contact each other.
[0040] As shown in FIG. 2B, the conductive layer 10 further
includes a third conductive portion 13. The direction from the
first conductive portion 11 toward the third conductive portion 13
is along the Y-direction.
[0041] The third element 23 includes a seventh semiconductor layer
23g of the first conductivity type, an eighth semiconductor layer
23h of the second conductivity type, and a ninth semiconductor
layer 23i of the second conductivity type. The seventh
semiconductor layer 23g is separated from the third conductive
portion 13 in the Z-direction. The eighth semiconductor layer 23h
is provided between the third conductive portion 13 and the seventh
semiconductor layer 23g in the Z-direction. The ninth semiconductor
layer 23i is provided between the third conductive portion 13 and
the eighth semiconductor layer 23h in the Z-direction and surrounds
the seventh semiconductor layer 23g and the eighth semiconductor
layer 23h along the X-Y plane. The impurity concentration of the
second conductivity type in the ninth semiconductor layer 23i is
lower than the impurity concentration of the second conductivity
type in the eighth semiconductor layer 23h. For example, the third
element 23 contacts the third conductive portion 13.
[0042] The conductor 40 further includes a second member 40b
positioned between the first element 21 and the third element 23 in
the Y-direction. A portion of the first insulating part 31 is
provided between the first element 21 and the second member 40b in
the Y-direction. The third insulating part 33 is provided between
the third element 23 and the second member 40b in the Y-direction.
For example, the third insulating part 33 is provided around the
third element 23 along the X-Y plane. For example, a portion of the
third insulating part 33 is provided between the first conductive
portion 11 and the third conductive portion 13 in the
Y-direction.
[0043] The semiconductor part 25a is provided between the first
insulating part 31 and the second member 40b in the Y-direction. A
semiconductor part 25c is provided between the third insulating
part 33 and the second member 40b in the Y-direction. For example,
the semiconductor part 25c is of the second conductivity type.
[0044] The direction from the second element 22 toward the fourth
element 24 is along the Y-direction. The direction from the third
element 23 toward the fourth element 24 is along the X-direction.
The fourth insulating part 34 is provided around the fourth element
24 along the X-Y plane. The structure of the fourth element 24 is,
for example, the same as the structure of the first element 21.
[0045] The first wiring part 51a is electrically connected to the
first semiconductor layer 21a. The second wiring part 51b is
electrically connected to the fourth semiconductor layer 22d. The
third wiring part 51c is electrically connected to the seventh
semiconductor layer 23g. The fourth wiring part 51d is electrically
connected to the semiconductor layer of the first conductivity type
of the fourth element 24.
[0046] As shown in FIG. 1 and FIG. 2A, in the Z-direction, the
first element 21 and the first insulating part 31 are provided
between the first conductive portion 11 and the first wiring part
51a, between the first conductive portion 11 and the first
insulating region 61, and between the first conductive portion 11
and the first connection wiring part 52a. In the Z-direction, the
second element 22 and the second insulating part 32 are provided
between the second conductive portion 12 and the second wiring part
51b, between the second conductive portion 12 and the second
insulating region 62, and between the second conductive portion 12
and the second connection wiring part 52b. As shown in FIG. 1 and
FIG. 2B, in the Z-direction, the third element 23 and the third
insulating part 33 are provided between the third conductive
portion 13 and the third wiring part 51c, between the third
conductive portion 13 and the third insulating region 63, and
between the third conductive portion 13 and the first connection
wiring part 52a.
[0047] The first conductive part 53a is connected between the first
connection wiring part 52a and the first wiring part 51a. The
second conductive part 53b is connected between the second
connection wiring part 52b and the second wiring part 51b. The
third conductive part 53c is connected between the first connection
wiring part 52a and the third wiring part 51c. The fourth
conductive part 53d is connected between the second connection
wiring part 52b and the fourth wiring part 51d. The electrical
resistances of the first to fourth conductive parts 53a to 53d each
are higher than the electrical resistances of the wiring parts and
higher than the electrical resistances of the connection wiring
parts. For example, the first to fourth conductive parts 53a to 53d
function as quenching resistances. For example, it is favorable for
the electrical resistances of the first to fourth conductive parts
53a to 53d each to be not less than 50 k.OMEGA. and not more than 2
M.OMEGA..
[0048] The first to fourth wiring parts 51a to 51d, the first
connection wiring part 52a, the second connection wiring part 52b,
and the first to fourth conductive parts 53a to 53d are
electrically isolated from the conductor 40. For example, as shown
in FIG. 2A, a portion of the first insulating region 61 is provided
between the conductor 40 and the first connection wiring part
52a.
[0049] The conductor 40 is electrically connected to the wiring
part 54. The position where the conductor 40 and the wiring part 54
are connected is arbitrary. The direction from the wiring part 54
toward one of the first to fourth wiring parts 51a to 51d is along
a direction parallel to the X-Y plane.
[0050] Examples of the materials of the components are described
below.
[0051] The first to fourth elements 21 to 24 include silicon. When
the first to fourth elements 21 to 24 include silicon, at least one
selected from the group consisting of arsenic, phosphorus, and
antimony may be used as the impurity of the first conductivity
type. Boron may be used as the impurity of the second conductivity
type.
[0052] The semiconductor parts 25a, 25b, and 25c include, for
example, silicon and boron. The materials of the semiconductor
parts 25a, 25b, and 25c may be the same or may be different from
each other.
[0053] The impurity concentrations of the semiconductor layers are,
for example, as follows.
[0054] The impurity concentration of the first conductivity type is
not less than 1.0.times.10.sup.18 atoms/cm.sup.3 and not more than
1.0.times.10.sup.21 atoms/cm.sup.3 for the first semiconductor
layer 21a, the fourth semiconductor layer 22d, and the seventh
semiconductor layer 23g. By setting this concentration range, the
electrical resistances of the first semiconductor layer 21a, the
fourth semiconductor layer 22d, and the seventh semiconductor layer
23g can be reduced; and the carrier loss in these semiconductor
layers can be reduced.
[0055] The impurity concentration of the second conductivity type
is not less than 1.0.times.10.sup.16 atoms/cm.sup.3 and not more
than 1.0.times.10.sup.18 atoms/cm.sup.3 for the second
semiconductor layer 21b, the fifth semiconductor layer 22e, and the
eighth semiconductor layer 23h. By setting this concentration
range, the second semiconductor layer 21b, the fifth semiconductor
layer 22e, and the eighth semiconductor layer 23h can have p-n
junctions respectively with the first semiconductor layer 21a, the
fourth semiconductor layer 22d, and the seventh semiconductor layer
23g; and depletion layers can spread easily in the second
semiconductor layer 21b, the fifth semiconductor layer 22e, and the
eighth semiconductor layer 23h.
[0056] The impurity concentration of the second conductivity type
is not less than 1.0.times.10.sup.13 atoms/cm.sup.3 and not more
than 1.0.times.10.sup.16 atoms/cm.sup.3 for the third semiconductor
layer 21c, the sixth semiconductor layer 22f, and the ninth
semiconductor layer 23i. By setting this concentration range,
depletion layers can spread sufficiently in the third semiconductor
layer 21c, the sixth semiconductor layer 22f, and the ninth
semiconductor layer 23i; and the light detection efficiency or the
light-receiving sensitivity can be increased.
[0057] The conductive layer 10 is a semiconductor layer of the
second conductivity type. The impurity concentration of the second
conductivity type in the conductive layer 10 is not less than
1.0.times.10.sup.17 atoms/cm.sup.3 and not more than
1.0.times.10.sup.21 atoms/cm.sup.3. The conductive layer 10 may
include a metal. For example, the conductive layer 10 includes at
least one selected from the group consisting of aluminum, copper,
titanium, gold, and nickel.
[0058] The first to fourth insulating parts 31 to 34 include at
least one selected from the group consisting of silicon, oxygen,
and nitrogen.
[0059] The first to fourth wiring parts 51a to 51d, the first
connection wiring part 52a, the second connection wiring part 52b,
and the wiring part 54 include at least one selected from the group
consisting of aluminum and copper. The first to fourth wiring parts
51a to 51d, the first connection wiring part 52a, the second
connection wiring part 52b, and the wiring part 54 may include an
aluminum compound.
[0060] The first to fourth conductive parts 53a to 53d include
polysilicon. The first to fourth conductive parts 53a to 53d may
further include an impurity of the first conductivity type or the
second conductivity type.
[0061] The first to third insulating regions 61 to 63 include at
least one selected from the group consisting of silicon, oxygen,
and nitrogen. The first to third insulating regions 61 to 63 each
may include multiple layers. For example, the first to third
insulating regions 61 to 63 each include a layer including silicon
oxide, a layer including silicon oxide, boron, and phosphorus, and
a layer including silicon oxide.
[0062] The conductor 40 includes, for example, at least one
selected from the group consisting of tungsten, polysilicon,
aluminum, copper, nickel, titanium, and chrome. The conductor 40
can be provided with conductivity thereby. The conductor 40 may
include an alloy including aluminum and copper.
[0063] Or, the conductor 40 includes at least one selected from the
group consisting of tungsten, aluminum, copper, nickel, titanium,
and chrome. Thereby, the light transmittance of the conductor 40
can be lower than the light transmittance of the third
semiconductor layer 21c and lower than the light transmittance of
the sixth semiconductor layer 22f.
[0064] Favorably, the conductor 40 includes at least one selected
from the group consisting of tungsten, aluminum, and copper.
Thereby, the conductor 40 can be provided with conductivity; and
the light transmittance of the conductor 40 can be lower than the
light transmittances of the semiconductor layers.
[0065] Examples of the lengths of the components will now be
described.
[0066] The thicknesses in the Z-direction of the first
semiconductor layer 21a, the fourth semiconductor layer 22d, and
the seventh semiconductor layer 23g are not less than 10 nm and not
more than 2000 nm.
[0067] The second semiconductor layer 21b, the fifth semiconductor
layer 22e, and the eighth semiconductor layer 23h are positioned
respectively at the lower portions of the first semiconductor layer
21a, the fourth semiconductor layer 22d, and the seventh
semiconductor layer 23g. The thicknesses in the Z-direction of the
second semiconductor layer 21b, the fifth semiconductor layer 22e,
and the eighth semiconductor layer 23h are not less than 10 nm and
not more than 5000 nm.
[0068] The thickness in the Z-direction of the third semiconductor
layer 21c is thicker than the total of the thickness in the
Z-direction of the first semiconductor layer 21a and the thickness
in the Z-direction of the second semiconductor layer 21b and is 15
.mu.m or less. The thickness in the Z-direction of the sixth
semiconductor layer 22f is thicker than the total of the thickness
in the Z-direction of the fourth semiconductor layer 22d and the
thickness in the Z-direction of the fifth semiconductor layer 22e
and is 15 .mu.m or less. The thickness in the Z-direction of the
ninth semiconductor layer 23i is thicker than the total of the
thickness in the Z-direction of the seventh semiconductor layer 23g
and the thickness in the Z-direction of the eighth semiconductor
layer 23h and is 15 .mu.m or less.
[0069] The length in the Z-direction of the first insulating part
31 is longer than the total of the thickness in the Z-direction of
the first semiconductor layer 21a and the thickness in the
Z-direction of the second semiconductor layer 21b and is 20 .mu.m
or less.
[0070] The length in the Z-direction of the second insulating part
32 is longer than the total of the thickness in the Z-direction of
the fourth semiconductor layer 22d and the thickness in the
Z-direction of the fifth semiconductor layer 22e and is 20 .mu.m or
less.
[0071] The length in the Z-direction of the third insulating part
33 is longer than the total of the thickness in the Z-direction of
the seventh semiconductor layer 23g and the thickness in the
Z-direction of the eighth semiconductor layer 23h and is 20 .mu.m
or less.
[0072] For example, the thicknesses in the Z-direction of the first
semiconductor layer 21a, the fourth semiconductor layer 22d, and
the seventh semiconductor layer 23g each are taken as T1. The
thicknesses in the Z-direction of the second semiconductor layer
21b, the fifth semiconductor layer 22e, and the eighth
semiconductor layer 23h each are taken as T2. The thicknesses in
the Z-direction of the third semiconductor layer 21c, the sixth
semiconductor layer 22f, and the ninth semiconductor layer 23i each
are taken as T3. The lengths in the Z-direction of the first
insulating part 31, the second insulating part 32, and the third
insulating part 33 each are taken as L1. In such a case, it is
favorable for the relationships of the following Formula (1) and
Formula (2) to be satisfied.
T1+1.1.times.T2<L1 (1)
L1<T1+T2+1.1.times.T3 (2)
[0073] By setting the length L1 to satisfy Formula (1), the flow
toward the conductor 40 of the carriers generated at each p-n
junction surface can be suppressed sufficiently. By setting the
length L1 to satisfy Formula (2), the formation of the first to
third insulating parts 31 to 33 is easy. Therefore, the yield of
the light detector 110 can be increased.
[0074] However, when the thickness T2 is greater than 10 times the
thickness T3, it is favorable for the relationships of the
following Formula (3) and Formula (4) to be satisfied.
T1+1.1.times.T2<L1 (3)
T1+T2+1.1.times.T3<L1 (4)
[0075] By setting the length L1 to satisfy Formula (3) and Formula
(4), the yield of the light detector 110 can be increased while
suppressing the flow toward the conductor 40 of the carriers
generated at each p-n junction surface.
[0076] It is favorable for the lengths in the Z-direction of the
first member 40a and the second member 40b each to be greater than
the thicknesses in the Z-direction of the third semiconductor layer
21c, the sixth semiconductor layer 22f, and the ninth semiconductor
layer 23i. The crosstalk can be reduced thereby. On the other hand,
it is favorable for the lengths in the Z-direction of the first
member 40a and the second member 40b each to be 20 .mu.m or less to
make the patterning of these members easy.
[0077] It is favorable for the distance in the X-direction between
the first insulating part 31 and the second insulating part 32 to
be 10 .mu.m or less. Thereby, the surface area in the X-Y plane of
the first element 21 and the second element 22 can be large; and
the light detection efficiency can be increased. On the other hand,
if the distance is too short, it is difficult to provide the first
member 40a. Therefore, it is favorable for the distance in the
X-direction between the first insulating part 31 and the second
insulating part 32 to be 0.5 .mu.m or more.
[0078] It is favorable for the side surfaces of the first
insulating part 31, the second insulating part 32, the first member
40a, and the second member 40b each to be oblique to the
Z-direction. In other words, it is favorable for the widths of the
first insulating part 31, the second insulating part 32, the first
member 40a, and the second member 40b to decrease toward the
conductive layer 10. According to such configurations, it is easy
to fill the insulating material or the conductive material when
forming the first insulating part 31, the second insulating part
32, the first member 40a, and the second member 40b. Therefore, the
yield of the light detector 110 can be increased.
[0079] FIG. 3A, FIG. 3B, FIG. 4A, and FIG. 4B are schematic
cross-sectional views illustrating manufacturing processes of the
light detector according to the first embodiment.
[0080] A semiconductor layer 20L of the second conductivity type is
formed on a semiconductor layer 10L of the second conductivity
type. For example, the semiconductor layer 20L is formed by
epitaxial growth of silicon. Multiple trenches that pierce the
semiconductor layer 20L are formed. For example, the trenches are
formed by reactive ion etching (RIE). Each of the trenches
surrounds a portion of the semiconductor layer 20L. Insulating
layers are formed in the trenches. For example, the insulating
layers are formed by chemical vapor deposition (CVD) using
tetraethoxysilane. As shown in FIG. 3A, an insulating layer 31L and
an insulating layer 32L are formed thereby. Heat treatment of the
semiconductor layer 20L may be performed when forming the
insulating layers. The defects of the semiconductor layer 20L
occurring when the trenches are formed can be repaired thereby.
[0081] A semiconductor layer of the first conductivity type and a
semiconductor layer of the second conductivity type are formed in
the portion of the semiconductor layer 20L surrounded with the
insulating layer by sequentially ion-implanting an impurity of the
first conductivity type and an impurity of the second conductivity
type. For example, a semiconductor layer 21L of the first
conductivity type and a semiconductor layer 22L of the second
conductivity type are formed inside the insulating layer 31L. A
semiconductor layer 24L of the first conductivity type and a
semiconductor layer 25L of the second conductivity type are formed
inside the insulating layer 32L. An insulating layer 61L which
covers the semiconductor layer 20L is formed by CVD. As shown in
FIG. 3B, an insulating layer 62L is formed on the insulating layer
61L. For example, the insulating layer 61L includes silicon oxide.
The insulating layer 62L includes silicon oxide, boron, and
phosphorus.
[0082] After melting the insulating layer 62L, the melted
insulating layer 62L is caused to solidify. The flatness of the
surface of the insulating layer 62L improves thereby. A
not-illustrated polysilicon layer is formed on the insulating layer
62L; and the polysilicon layer is patterned. The conductive layers
that correspond to the quenching resistances are formed thereby. As
shown in FIG. 4A, an insulating layer 63L is formed by CVD on the
insulating layer 62L and the conductive layer. The insulating layer
63L includes, for example, silicon oxide.
[0083] A trench is formed between the insulating layers piercing
the semiconductor layer 20L. The trench reaches the semiconductor
layer 10L. A metal layer 40L is formed in the trench by CVD. The
metal layer 40L includes, for example, tungsten. Then, openings are
formed by removing a portion of the insulating layer 61L, a portion
of the insulating layer 62L, and a portion of the insulating layer
63L by RIE. The semiconductor layers of the first conductivity type
are exposed via the openings. A metal layer 50L is formed on the
insulating layer 63L. The openings are filled with the metal layer
50L. For example, the metal layer 50L includes aluminum and is
formed by sputtering. As shown in FIG. 4B, multiple wiring parts
are formed by patterning the metal layer 50L. Thus, the light
detector according to the first embodiment is manufactured.
[0084] According to the first embodiment, the performance of the
light detector 110 can be improved as follows.
[0085] In the first embodiment, the conductor 40 is conductive and
is electrically connected to the conductive layer 10. For example,
a portion of the first member 40a is provided between the first
conductive portion 11 and the second conductive portion 12.
Thereby, the potential of the conductive layer 10 can be controlled
via the conductor 40. The control of the potential of the
conductive layer 10 is easy. Also, by providing the first
insulating part 31 and the second insulating part 32, the
occurrence of the leakage current between the conductor 40 and the
first element 21 and the occurrence of the leakage current between
the conductor 40 and the second element 22 can be suppressed.
[0086] Or, in the first embodiment, the light transmittance of the
first member 40a is lower than the light transmittance of the third
semiconductor layer 21c and lower than the light transmittance of
the sixth semiconductor layer 22f. For example, the light
transmittance of the first member 40a is lower than the light
transmittance of the first insulating part 31 and lower than the
light transmittance of the second insulating part 32. Thereby,
secondary photons that are generated in one of the first element 21
or the second element 22 can be suppressed from entering the other
of the first element 21 or the second element 22. As a result, the
crosstalk can be reduced.
[0087] The configurations described above may be combined. Namely,
in the first embodiment, the conductor 40 is conductive; the first
insulating part 31 and the second insulating part 32 are provided;
and the light transmittance of the first member 40a is lower than
the light transmittance of the third semiconductor layer 21c and
lower than the light transmittance of the sixth semiconductor layer
22f. Accordingly, the crosstalk can be reduced while making the
control of the potential of the conductive layer 10 easy and
suppressing the occurrence of the leakage current.
Second Embodiment
[0088] FIG. 5A and FIG. 5B are schematic cross-sectional views
illustrating a light detector according to a second embodiment.
[0089] In the light detector 120 according to the second embodiment
shown in FIG. 5A and FIG. 5B, the first insulating part 31 and the
second insulating part 32 contact the first member 40a of the
conductor 40. The first insulating part 31 and the third insulating
part 33 contact the second member 40b of the conductor 40.
[0090] Or, one of the semiconductor part 25a or 25b may be provided
between the first insulating part 31 and the first member 40a or
between the second insulating part 32 and the first member 40a. One
of the semiconductor part 25a or 25c may be provided between the
first insulating part 31 and the second member 40b or between the
third insulating part 33 and the second member 40b.
[0091] In the light detector 120, compared to the light detector
110, the length in the X-direction of the first member 40a is long;
and the length in the Y-direction of the second member 40b is long.
According to the second embodiment, the following effects are
obtained in addition to the effects of the first embodiment.
[0092] When the conductor 40 is conductive, the electrical
resistance of the conductor 40 can be reduced. Thereby, the
fluctuation of the potential of the conductive layer 10 can be
suppressed when controlling the potential of the conductive layer
10 via the conductor 40. Or, when the light transmittance of the
conductor 40 is lower than the light transmittances of the
semiconductor layers, the secondary photons do not pass through the
conductor 40 easily. The crosstalk can be reduced thereby.
[0093] According to the second embodiment, compared to the first
embodiment, the width of the trench formed between the insulating
layers 31L and 32L can be wide when forming the metal layer 40L
shown in FIG. 3B and FIG. 4A. In other words, compared to the first
embodiment, the ratio of the width of the trench to the depth of
the trench is large. Thereby, it is easy to form the trench and the
metal layer 40L. As a result, for example, the yield of the light
detector 120 can be increased.
Third Embodiment
[0094] FIG. 6 is a schematic plan view illustrating a light
detector according to a third embodiment.
[0095] In the light detector 130 according to the third embodiment
shown in FIG. 6, the first connection wiring part 52a and the
second connection wiring part 52b do not overlap the conductor 40
in the Z-direction.
[0096] For example, multiple conductors 40 are provided in the
X-direction. When viewed from the Z-direction, the first connection
wiring part 52a is positioned between one of the multiple
conductors 40 and another one of the multiple conductors 40 in the
X-direction. When viewed from the Z-direction, the second
connection wiring part 52b is positioned between the other one of
the multiple conductors 40 and yet another one of the multiple
conductors 40 in the X-direction.
[0097] According to the light detector 130, the parasitic
capacitance that occurs between the connection wiring part and the
conductor 40 can be reduced. Therefore, according to the third
embodiment, the following effects are obtained in addition to the
effects of the first embodiment or the second embodiment. For
example, the sensitivity when each element detects the light can be
increased. Also, the effects on the time constant of the output
pulse due to the parasitic capacitance can be reduced; and the
crosstalk due to the parasitic capacitance can be suppressed.
Fourth Embodiment
[0098] FIG. 7 is a schematic plan view illustrating a light
detector according to a fourth embodiment.
[0099] The light detector 140 according to the fourth embodiment
shown in FIG. 7 includes a first member 41 and a second member
42.
[0100] The first member 41 includes a first region 41a provided
between the first element 21 and the second element 22 and between
the third element 23 and the fourth element 24 in the X-direction.
The first member 41 further includes multiple third regions 41c.
One end in the X-direction of each third region 41c is connected to
the first region 41a.
[0101] The second member 42 includes a second region 42b provided
between the first element 21 and the third element 23 in the
Y-direction. The second region 42b is positioned between the third
regions 41c in the Y-direction. The first element 21 is positioned
between the second region 42b and one of the multiple third regions
41c. The third element 23 is positioned between the second region
42b and another one of the multiple third regions 41c.
[0102] The second member 42 further includes a fourth region 42d.
One end in the X-direction of the second region 42b is connected to
the fourth region 42d. The first element 21 and the third element
23 are positioned between the first region 41a and the fourth
region 42d in the X-direction.
[0103] For example, the first member 41 and the second member 42
are conductive and are electrically connected to the conductive
layer 10. For example, the first member 41 and the second member 42
include tungsten.
[0104] The first member 41 and the second member 42 are separated
from each other. Thereby, the semiconductor part 25a and the
semiconductor part 25c are linked between the first region 41a and
the other end of the second region 42b. The multiple wiring parts
54 are electrically connected respectively to the first member 41
and the second member 42.
[0105] The first connection wiring part 52a does not overlap the
first member 41 or the second member 42 in the Z-direction. In
other words, when viewed from the Z-direction, the position of the
first connection wiring part 52a is different from the position of
the first member 41 and the position of the second member 42. The
position in the X-direction and the position in the Y-direction of
each portion of the first connection wiring part 52a are different
from the position in the X-direction and the position in the
Y-direction of the first member 41. Also, the position in the
X-direction and the position in the Y-direction of each portion of
the first connection wiring part 52a are different from the
position in the X-direction and the position in the Y-direction of
the second member 42. For example, when viewed from the
Z-direction, portions of the first connection wiring part 52a are
positioned between the fourth region 42d and the third regions 41c.
When viewed from the Z-direction, another portion of the first
connection wiring part 52a is positioned between the first region
41a and the second region 42b. The parasitic capacitance between
the first connection wiring part 52a and the first member 41 and
the parasitic capacitance between the first connection wiring part
52a and the second member 42 can be reduced thereby.
[0106] For example, the light transmittances of the first member 41
and the second member 42 each are lower than the light
transmittances of the third semiconductor layer 21c, the sixth
semiconductor layer 22f, and the ninth semiconductor layer 23i. As
shown in FIG. 7, the position in the X-direction of the gap between
the first region 41a and the second region 42b is different from
the position in the X-direction of the gap between the third region
41c and the fourth region 42d. According to the fourth embodiment,
in addition to the effects of at least one of the first to third
embodiments, the secondary photons that are generated in one
element can be suppressed from entering an adjacent element. As a
result, the crosstalk can be reduced further.
Fifth Embodiment
[0107] FIG. 8 is a schematic plan view illustrating a light
detector according to a fifth embodiment.
[0108] FIG. 9A and FIG. 9B are schematic cross-sectional views
illustrating the light detector according to the fifth
embodiment.
[0109] FIG. 9A is an A1-A2 cross section of FIG. 8. FIG. 9B is a
B1-B2 cross section of FIG. 8.
[0110] The light detector 150 shown in FIG. 8, FIG. 9A, and FIG. 9B
includes an insulating layer 45 and first to fourth connection
parts 55a to 55d.
[0111] The conductor 40 is conductive in the light detector 150
according to the fifth embodiment. As shown in FIG. 8, the first to
fourth connection parts 55a to 55d are electrically connected to
the conductor 40. The first to fourth wiring parts 51a to 51d are
electrically connected respectively to the first to fourth
connection parts 55a to 55d via the first to fourth conductive
parts 53a to 53d.
[0112] As shown in FIG. 9A and FIG. 9B, the insulating layer 45 is
provided between the conductor 40 and the conductive layer 10. The
conductor 40 is electrically isolated from the conductive layer 10
by the insulating layer 45.
[0113] For example, the insulating layer 45 includes at least one
selected from the group consisting of silicon, oxygen, and
nitrogen. For example, the first to fourth connection parts 55a to
55d include at least one selected from the group consisting of
aluminum, tungsten, copper, and titanium.
[0114] The conductor 40 is used as wiring in the light detector
150. According to the fifth embodiment, in addition to the effects
of at least one of the first to fourth embodiments, the amount of
wiring provided on each element can be reduced. As a result, for
example, the light detector can be downsized.
Sixth Embodiment
[0115] FIG. 10A and FIG. 10B are schematic cross-sectional views
illustrating a light detector according to a sixth embodiment.
[0116] In the light detector 160 according to the sixth embodiment
shown in FIG. 10A and FIG. 10B, the first member 40a contacts the
first insulating part 31 and the second insulating part 32. The
second member 40b contacts the first insulating part 31 and the
third insulating part 33.
[0117] Or, a semiconductor part 25 may be provided between the
first insulating part 31 and the first member 40a or between the
second insulating part 32 and the first member 40a. The
semiconductor part 25 may be provided between the first insulating
part 31 and the second member 40b or between the third insulating
part 33 and the second member 40b.
[0118] In the light detector 160, compared to the light detector
120, the length in the X-direction of the first member 40a is long;
and the length in the Y-direction of the second member 40b is long.
According to the sixth embodiment, the following effects are
obtained in addition to the effects of at least one of the first to
fifth embodiments.
[0119] When the conductor 40 is conductive, the electrical
resistance of the conductor 40 can be reduced. Or, when the light
transmittance of the conductor 40 is lower than the light
transmittances of the semiconductor layers, the secondary photons
do not pass through the conductor 40 easily. The crosstalk can be
reduced thereby.
Seventh Embodiment
[0120] FIG. 11A and FIG. 11B are schematic cross-sectional views
illustrating a light detector according to a seventh
embodiment.
[0121] In the light detector 170 according to the seventh
embodiment shown in FIG. 11A and FIG. 11B, the first semiconductor
layer 21a and the second semiconductor layer 21b contact the first
insulating part 31. The fourth semiconductor layer 22d and the
fifth semiconductor layer 22e contact the second insulating part
32. The seventh semiconductor layer 23g and the eighth
semiconductor layer 23h contact the third insulating part 33. Other
than the points where the first to third insulating parts 31 to 33
contact the semiconductor layers, the configuration of the light
detector 170 is, for example, similar to that of the light detector
110.
[0122] According to the seventh embodiment, similarly to the first
embodiment, the potential of the conductive layer 10 is
controllable via the conductor 40 if the conductor 40 is
conductive. Also, the occurrence of the leakage current between the
conductor 40 and the first element 21 and the occurrence of the
leakage current between the conductor 40 and the second element 22
can be suppressed by the first insulating part 31 and the second
insulating part 32. Or, the crosstalk can be reduced when the light
transmittance of the first member 40a is lower than the light
transmittance of the third semiconductor layer 21c and lower than
the light transmittance of the sixth semiconductor layer 22f.
[0123] The semiconductor layers similarly may contact the first to
third insulating parts 31 to 33 in the light detectors according to
any of the second to sixth embodiments.
Eighth Embodiment
[0124] FIG. 12 is a schematic view illustrating a lidar (Laser
Imaging Detection and Ranging) device according to an eighth
embodiment.
[0125] The embodiment is applicable to a long-distance subject
detection system (LIDAR) or the like including a line light source
and a lens. The lidar device 5001 includes a light projecting unit
T projecting laser light toward an object 411, and a light
receiving unit R (also called a light detection system) receiving
the laser light from the object 411, measuring the time of the
round trip of the laser light to and from the object 411, and
converting the time into a distance.
[0126] In the light projecting unit T, a laser light oscillator
(also called a light source) 404 produces laser light. A drive
circuit 403 drives the laser light oscillator 404. An optical
system 405 extracts a portion of the laser light as reference
light, and irradiates the rest of the laser light on the object 411
via a mirror 406. A mirror controller 402 projects the laser light
onto the object 411 by controlling the mirror 406. Herein,
"project" means to cause the light to strike.
[0127] In the light receiving unit R, a reference light detector
409 detects the reference light extracted by the optical system
405. A light detector 410 receives the reflected light from the
object 411. Based on the reference light detected by the reference
light detector 409 and the reflected light detected by the light
detector 410, a distance measuring circuit 408 measures the
distance to the object 411. An image recognition system 407
recognizes the object 411 based on the results measured by the
distance measuring circuit 408.
[0128] The lidar device 5001 employs light time-of-flight ranging
in which the time of the round trip of the laser light to and from
the object 411 is measured and converted into a distance. The lidar
device 5001 is applied to an automotive drive-assist system, remote
sensing, etc. Good sensitivity is obtained particularly in the
near-infrared region when the light detectors of the embodiments
described above are used as the light detector 410. Therefore, the
lidar device 5001 is applicable to a light source of a wavelength
band invisible to humans. For example, the lidar device 5001 can be
used for obstacle detection in a vehicle.
[0129] FIG. 13 is a drawing for describing the detection of the
detection object of the lidar device.
[0130] A light source 3000 emits light 412 toward an object 600
which is the detection object. A light detector 3001 detects light
413 which passes through the object 600, is reflected by the object
600, or is diffused by the object 600.
[0131] For example, the light detector 3001 realizes a
highly-sensitive detection when the light detector according to the
embodiment described above is used. It is favorable to provide
multiple sets of the light detector 410 and the light source 404
and to preset the arrangement relationship in the software (which
is replaceable with a circuit). For example, it is favorable for
the arrangement relationship of the sets of the light detector 410
and the light source 404 to be at uniform spacing. Thereby, an
accurate three-dimensional image can be generated by the output
signals of each light detector 410 supplementing each other.
[0132] FIG. 14 is a schematic top view of a vehicle including the
lidar device according to the eighth embodiment.
[0133] A vehicle 700 according to the embodiment includes the lidar
devices 5001 at four corners of a vehicle body 710. Because the
vehicle according to the embodiment includes the lidar devices at
the four corners of the vehicle body, the environment in all
directions of the vehicle can be detected by the lidar devices.
[0134] According to the embodiments described above, a light
detector can be provided in which the performance is improved.
[0135] In the specification of the application, "perpendicular" and
"parallel" refer to not only strictly perpendicular and strictly
parallel but also include, for example, the fluctuation due to
manufacturing processes, etc. It is sufficient to be substantially
perpendicular and substantially parallel.
[0136] Hereinabove, embodiments of the invention are described with
reference to specific examples. However, the invention is not
limited to these specific examples. For example, one skilled in the
art may similarly practice the invention by appropriately selecting
specific configurations of components included in the light
detector such as the conductive layer, the element, the insulating
part, the first member, the wiring part, the connection wiring
part, the conductive part, the connection part, the insulating
region, etc., from known art; and such practice is within the scope
of the invention to the extent that similar effects can be
obtained.
[0137] Further, any two or more components of the specific examples
may be combined within the extent of technical feasibility and are
included in the scope of the invention to the extent that the
purport of the invention is included.
[0138] Moreover, all light detector, all light detection systems,
all lidar devices, and all vehicles practicable by an appropriate
design modification by one skilled in the art based on the light
detector, the light detection system, the lidar device, and the
vehicle described above as embodiments of the invention also are
within the scope of the invention to the extent that the spirit of
the invention is included.
[0139] Various other variations and modifications can be conceived
by those skilled in the art within the spirit of the invention, and
it is understood that such variations and modifications are also
encompassed within the scope of the invention.
[0140] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the inventions. Indeed, the novel
embodiments described herein may be embodied in a variety of other
forms; furthermore, various omissions, substitutions and changes in
the form of the embodiments described herein may be made without
departing from the spirit of the inventions. The accompanying
claims and their equivalents are intended to cover such forms or
modifications as would fall within the scope and spirit of the
invention.
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